1. Field of the Invention
The present disclosure relates to an input device which has a capacitive coupling type touch sensor function for allowing coordinates input to a screen, and a display device including this input device.
2. Background Art
There is an input device that has a screen input function for inputting information by allowing, for example, a finger of a user to make contact with a display screen (hereinbelow, referred to as a “touch operation” or merely referred to as “touch”). A display device that is provided with such an input device having a screen input function is used in mobile electronic devices such as a PDA (Personal Digital Assistance) and a mobile terminal, various home electric appliances, and stationary customer guide terminals such as an unattended reception machine and the like. As for such an input device using touch, there are known input devices of various systems such as a resistive film system which detects a change in resistance in a touched part, a capacitive coupling system which detects a change in capacitance, and an optical sensor system which detects a change in an amount of light in a part shielded by touch.
In comparison with the resistive film system and the optical sensor system, the capacitive coupling system has the following advantages. For example, both the resistive film system and the optical sensor system have relatively low light transmittance of approximately 80%. On the other hand, the capacitive coupling system has relatively high light transmittance of approximately 90% at which image quality of a display image is not likely to decrease. In addition, according to the resistive film system which detects a touch position based on a mechanical contact between resistive films, the resistive films may be deteriorated or damaged by the mechanical contact. However, the capacitive coupling system does not require a mechanical contact between detection electrodes and other electrodes or the like, and thus the durability is relatively high.
Unexamined Japanese Patent Publication No. 2011-138154 (PTL 1) discloses this type of capacitive coupling type input device, for example. PTL 1 discloses a structure of floating electrodes disposed apart from each other in an area between detection electrodes, and provided with a natural number multiple pitch of an arrangement pitch of pixel electrodes.